Venturi tubes are used in fuel supply modules of vehicles. For example, U.S. Pat. No. 6,951,208 shows a system having a reservoir that is disposed in a vehicle's fuel tank. A fuel pump is provided in the reservoir for pumping fuel from the reservoir to the engine of the vehicle. The fuel pump also operates a jet pump that draws fuel from the tank into the reservoir to ensure that the reservoir is replenished with fuel. The jet pump includes a venturi tube associated with a nozzle in the conventional manner to draw fuel through a jet valve into the reservoir.
It is important that the venturi tube has a smooth internal surface (flow surface) for optimum fluid flow through the tube. A typical manufacturing method to mold a venturi tube 10 is shown in FIG. 1. Based on the geometry of the tube 10, core pins and are required to enter a mold from both ends 12, 14 such that the two core pins and mate with each other at a mating location A. At the mating location A, flash can occur, causing the flow surface 16 to no longer be smooth, but to have a small wall protruding into the fluid path. The direction of fluid flow is indicted by arrow B.
Thus, there is need to provide a method of manufacturing a venturi tube with a flow surface that does not interrupt fluid flow in the flow direction.